1. Field of the Invention
The invention relates to methods and portable apparatus for efficiently melting sulfur.
2. Description of the Prior Art
A variety of methods and apparatus have been proposed for melting sulfur or extracting sulfur from ore. The proposed systems utilize various types of hoppers into which the sulfur bearing ore is dumped and gravity feed systems whereby the sulfur passes through chambers having heated walls or chambers containing hot water or steam to accomplish melting of the sulfur.
For example, U.S. Pat. No. 4,027,656 discloses a system in which solid sulfur is gravity fed into one or more heated vertical sulfur melt tubes. The solid sulfur is maintained within the tubes by means of an external heated plate disposed at a lower end of the melt tubes. The overburden weight of the sulfur within the hopper forces the sulfur into the tubes and against the heated walls of the tubes, whereat the sulfur melts and flows due to gravity in liquid form downward along the walled surfaces of the melt tubes. The melted sulfur is conducted into a heated trough and is conveyed in liquid form for storage or use. Reliance on overburden to produce the pressure forcing the sulfur against the heated walls and bottom results in a very tall hopper requiring expensive equipment to fill the hopper. Due to varying overburden, the pressure and hence the melting rate, varies substantially.
U.S. Pat. No. 1,512,230 discloses a system for extracting sulfur from ore. This system includes a pressurized chamber into which steam and/or hot water are injected after the chamber has been loaded with sulfur ore. The chamber has a bottom plate having a number of annular grooves therein. A plurality of discharge openings are disposed along bottoms of the annular grooves. The hot water and steam melts sulfur from the ore. A screen performs the function of filtering debris from raw ore. Melted sulfur is forced through the screen by the steam process. Sulfur flows from the discharge openings into a collecting funnel.
U.S. Pat. No. 3,838,979 discloses a system in which sulfur is recovered from ore which is heated within a sulfur recovery vessel to produce sulfur vapor. The sulfur vapor is then condensed within the vessel by direct contact with cold incoming ore. The sulfur product is collected from the condensed sulfur vapor and remaining gases recycled to the vessel.
U.S. Pat. No. 1,993,973 discloses a sulfur melting system including a hopper into which pulverized sulfur is loaded. A perforated retaining member or grate is provided at the bottom of the hopper, beneath which a trough is disposed. Steam heated coils heat the trough and the retaining member, and further heat the sulfur by radiation so that sulfur melts, then falls into the heated trough, and can be removed in liquid form for use or storage.
None of the above systems for melting sulfur are efficient due to the fact that when sulfur comes in contact with a heated surface, it melts readily, but the melted sulfur acts as an excellent insulator which prevents further melting of sulfur which is not in immediate intimate contact with the heated surface of the melting chamber.
Accordingly, it is an object of the invention to provide a system for melting sulfur more effectively than the systems of the known prior art.
It is yet another object of the invention to provide a sulfur melting system which transfers heat from a heater to sulfur more efficiently than prior sulfur melting systems.
Still another object of the invention is to provide a low cost sulfur melting apparatus which produces melted sulfur at a high rate.
A further object of the invention is to provide a sulfur melting system which more uniformly melts sulfur than prior sulfur melting systems.
A yet further object of the invention is to provide a low cost, portable efficient sulfur melting system which can be utilized to melt powdered sulfur for use in various field and construction activities.
The sulfur melting systems of the prior art require gravity flow systems or pumps to convey melted sulfur to a storage container or utilization device, adding expense to the systems.
Therefore, a still further object of the invention is to provide a sulfur melting system which obviates the need for gravity flow or pump-type melted sulfur removal systems.
A novelty search directed to the present invention uncovered, in addition to the above mentioned patents, U.S. Pat. Nos. 1,508,355, 2,149,373, 1,713,543, 3,594,416 directed to various melting systems and U.S. Pat. Nos. 3,501,890, 3,589,276 and 4,041,123 directed to various compacting apparatus.